The invention disclosed herein relates to buildings and to the construction field. More specifically it relates to the construction and use of assembled frames which are provided with and/or are adapted to receive separate releasable portions of the frame. One obvious use of the invention is in connection with windows for a building. Such windows may be storm windows as well as more premanent installations. Not only is the invention valuable in connection with windows but may be useful in connection with other framed portions of a building such as doors, etc. The invention relates to the complete window construction as well as to its several components. The invention is especially characterized by an extrusion of moldable plastic having a rigid portion and integral flexible locking and sealing projections or flanges.